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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3ca8c8b20833c83b0f4a5814de247498e765bad3fbf6ae6c8816cb10ac6c7a5' 
  AND token = 'BTJLhTptkq1KEHzgi2fz/8ra9LYiTQG1C3A6YdDXll0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}