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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f4ab5db58f53a5414e4a59c06ee6138fbe98af900bfac1b2d4647f9ab2a72f4' 
  AND token = '7cSiBrDIxjL8xx5z5JvePtsFeybCC6r9I5EjDk2DS2Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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