SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5d05d467da8e3d108a7a2c43f7eadbb04dc84bf4d8c4c5e83d87a03fb501cb4' 
  AND token = 'p6BPQNA6ausc+2EMr+MUMwYJyCRYfEpscWPY1cuxBc8=' 
  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"
    }
  }
}