SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '388eb5abdbef4edec0ca819ed5185c1273ad9e186bd760d10592676a03a409a2' 
  AND token = 'lz7A7qVTTci6gZeun9b9J2PdFKedUjOZWKDioLuXjM4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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