SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90546951d6e90c72798350c0149bb8bd52d891faf680bf3108a57d65281d9325' 
  AND token = 'th5Ne9vmrIXCIRmgiBWsHrnCgMS+A4Qw+qRqfs/6iGQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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