SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec653404fd2fab3b65965062e17af148b4a113533dd40a2e8a1d834ab48ce790' 
  AND token = '8hQ6dZ+dGBvvHIleU8mOHPFIFkjXIANBwq1NPn+H4bM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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