SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb8234b97e5af8f7d83d3c600f52a8e28469662d09139ce03125cda89cb6ee45' 
  AND token = 'GqgtMk8fR6epFHwwQJUnK3fq/oBvu01s66JJZEGZLts=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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