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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f9b5b3f0b049f3991ad439cea0c6b86f4ea6e1210a6eb45ceef578bec0719bf' 
  AND token = 'QZ2kONJWp0kwTcnLBVF0sO0kyn8BQh+A1ylrx7FY0Ik=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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