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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4ff82e10e87011a587273e1607eec5ed9d76ff3cc0ddc8bca1c0f0ab2b7c9bc' 
  AND token = 'MO1Uc/yMxpQF7ZOpO5xSgb+5Kkgx0hFpibmlh1IQY88=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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