SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '589faa8637d00da8ff0b278779bb5647357cfed6a884c78a65c321d38f517d42' 
  AND token = 'eQLi0x8DO8YgU4VDxmXkMNkMWgsZFPispkSCmjbfR4I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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