SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b83d76432ea1a2c55fcb463da843b5df5483fc9fd643f3454151052f91063881' 
  AND token = '54hljMFlnSfRfj2tuArCYgcz0iBwHEG9aGOVb/JQ9ck=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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