SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e50728cb25b112c2b475305971f645db539c9cec3878e94118fbf238c8cca94' 
  AND token = 'nyXbAcAPQSzMdP6gP5r/sb3ZceDjPLI1ZsIUkSYzg/M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00072

JSON explain

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