SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f52bbe7aaad52d8114b8adc804baa3e23a51529340a5be8675cb88c47d8b9c6f' 
  AND token = 'pbDWcFtfRrriMtW46FgCBes3BtWRczwYM/87DE9uRRc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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