SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b68532b7dddd1d618ddacdb7a55920823479048c3e3362843bdbe4b8212f9ea9' 
  AND token = '4wDiuLaNzr/NSr1a2mKYGp+8LtTkpwr30if+VBUnqBs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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