SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'feffd9a519696d84a5d1c08a2876fac54259e8cb2501e3abe8119290d564d79c' 
  AND token = 'uGzqPAoEaUoq2iXamtE54lgF4DJO2xZA+EMQoyJaw20=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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