SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9681a01c879399c9371cb66230c3adfad22f52f1b813eaae3b790b4eb823a84' 
  AND token = 'EdR3z4xFg6JuCoRJUJWCqGfaZmuVHwemxySi8lsVBCY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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