SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bbbe199051d11ebea015b6a6f7a9e9ab1d58bb4492fd6059eda7b015dde74453' 
  AND token = '5gajkjLPbquMBDZ5gNpoasKuYzkJp45sMLHcnLi2sJ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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