SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29fa4543ebca88991df1747f3766d9e008f6c97b6c5c591f1a4e377947820b6a' 
  AND token = 'AF62HZg02ozav/W6+1r6ZS0YaRvQfaDKGV+JRz4Qexc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}