SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '464049814667624ef44beb115e0fda0df34b7a3b2dbc75ff7374083348527af2' 
  AND token = '4ei1suDws85wAmbANAf/LWtvV+lXLoegl8zyzkw5VPc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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