SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a7cead885950acafc083ecb14c7bac81e066b47b588e24a59202f5e9e31b775' 
  AND token = '6Lr2KYEZzf6ZyflFMU4vwzEmEnI7JNdLhYDdUpNv85c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}