SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f26e78a1dd39d523dd93d67abb871dfa3960ce375f97dfcad8b79584769b4051' 
  AND token = 'vO3CGBTpTWn34vjy3q4qH0r+A87pFy09BD7ZLXYYwug=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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