SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3b9fbb493082442f635b5c237781673bc795f1c332307e41b7cbd851f554c03' 
  AND token = 'POkQp1ujQHwmuNAYqp6WVp65SRjFnNk9nchKVL61zWg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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