SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a27bcf961ec13a61042703bcadf584308e6da9216b8cfce67a6986414634539' 
  AND token = 'bF6XqyDYzsOntzDy1cQNo2xU5iP+20wICs3Y+QuczrM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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