SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2d5198db66f79d1711c53123204b554da6c19a4313c7138b7a3203a1cbfe68a' 
  AND token = 'lEmnspQh0F7EsDP2AquPFlG3epzi7M0uv0pkRxj358w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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