SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '803f72f1218ccd0e134ed43d74c16656fc657d16954aaf1a9e234c5e7ec747b8' 
  AND token = '+OixH7kHxNQi0Mgzwiiltjb9vvx1vt8oVgPd+zV65Kc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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