SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab36aa09f021f8027cf10af260eba633fac06c0c3d576b8fa09b56661e965a05' 
  AND token = '9i005bKDs5KX9LdprhvrMujkCpfdw2CIDCBQOXQXHsY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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