SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '974cfb5564c5571fbe3b3a1d6fbe7d4f21364b34aa46e19127fa8f962edcdf5a' 
  AND token = 'qnUzzpgfqSxvudIRYSvkOB34a+RF/n6ijwzBfRd7Wi8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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