SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '310a96522682014fdbf4d801aac47066df817ecbb50ca5c2183d92c991a9b358' 
  AND token = 'S0ZUKpu2IkROalhu+VVt72Qj28pkgkDXGWqnw94f5mY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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