SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0a9897c76955025460fdb1eeacf0b7dc6051418838baeeb2cc2976e73f175267' 
  AND token = '5TbHnMueS35d3EyCAadH3KJqR+JNlJ6qZMA1c7+WRbA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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