SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bcdca14d85836d8892398114a6884e34e687a0197cc70e075015ffdf9ab10b1b' 
  AND token = 'trALY8vouqVQtIF/cMJCojjDjC/W2dIzlkwFyZOa+jA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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