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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b54163c7c8d1c6ee9acd07b623b0c1b01f7c79a54b77f2ad04c546f641fe8d27' 
  AND token = 'jpCdfNaMgexPiYhxhzKTDtuiT6pC256eQaDi0k0fYTQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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