SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b0048a1bcd76e4f4a2b10af6b2710551b365798ef5742f11ff874c8d6a831498' 
  AND token = 'XQVZg4600xPuc/3Nf8A90ZFvy2+HDLhsbJ+NW3OtzhY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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