SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2cf9286502a34ca2e484a647303149eefe524575abe1a98b638c1482205fec76' 
  AND token = 'AvxxisdXj28qQN8tZ5452wSNeXxBU96+XVFyYbOElOg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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