SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87f6e95e229d329c2a2b7e63a7d9b66b6a08a49f82f5aaaf7d391630e7fa93e0' 
  AND token = 'MUuCsiuMcUIAgjwAqFBNAaztzR/R/T4Umf6YMz35AhE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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