SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ee052be2d39370814fa4642ba62a46f412d6b7d0e8b815994418eb8e3d89e78' 
  AND token = '0xU3Y6mKsyNwkSTGvjjPkI+zTGPwx5rVuiPggoRQHaQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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