SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '923b8b5d68201f9bb718d60e06efb0fef2caa475ffde283b6ad1ee2269de6332' 
  AND token = 'EWz9LBKI7fBqQBnTgdEVPduhItth4jgiKyaVSfY5UOQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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