SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7999deba5d98b807413ec7c1dc30e02af34f4d655122d4b1bdeaba212e3126d0' 
  AND token = '8guYH5P8uPyO4ImnVjWjK3vDeBLa2cxr/85ddG8D5nc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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