SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '890e457859f02f05154dfa6f7254614e4ec3dcc42bad339e4e89199391b9abcf' 
  AND token = 'ahjLBMbc7cHJ/gKTbso1PHgdGiGdtFW2csEgQ1YH9Vo=' 
  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"
    }
  }
}