SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '151fcfe01aa3e3c718408181a58776dc1123cde4158c6b570a7af1eb51047bc2' 
  AND token = 'D+IqzUOMeu3LySil6LtxFgM0gAJ/arYuBqwuU1da/is=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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