SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e81fe51597576629af7bac4b182ce1a7c4f3e3ce0c9dcebc687e9ab64bbf2b8b' 
  AND token = 'erjIpXjewh7qZPFo6Pjh4K0y0QSBZjmu3u2fCDN9aqQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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