SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '353b6fe7f72ee074a050d495e5d2f468441fb0841e223a3643c28b72674a643e' 
  AND token = 'kmrpHg8GBa75qYcZK4ytWZNS8XfA1g8CPqqBN/b98L0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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