SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b006e9b37d768a2c6f5430332d6700a29587a5a7e308e841d262edf43ef8f79e' 
  AND token = 'ssNlu+qRBEQ7jW5eRlRvF5BYSzYinKHFPXHGmKbTcGk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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