SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4cac0fed47e64042b243660303b6db2761aaab73a3600260037cbdce891ea03c' 
  AND token = 'MUeA3FjxjjGXPirDSDuHhruV86ujdmrcOcJmFJ959Fk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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