SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '619cec4bb8336f4caf586f778a0f222e2e4fbd6576ea7d3c7d997db65ea9171b' 
  AND token = 'klV+yq2gy0cdx+HSo/BiiEy+lkhUmvu2MQujGH+cTQY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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