SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '387ec0e1a8627d580cae92719d515272e6414388f49326d22e6710aefbbcb453' 
  AND token = '7yuKrqTyFBIlLg65CRrTtxOfPbNhyrwejqzdXQ4zZ4Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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