SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34934a1c3de0782373dbf8dd0ebd4625fcaee837ac5b7bafd56c1190c6df6b99' 
  AND token = 'RmERxKJaCuz+kmumL2WmgfdQmaRp8bPWnzbGV60gf9E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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