SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b9d17095bef1c2697c58856be256ec83637037da0768ff3fa79b610113c5d6d1' 
  AND token = 'oo2kAEqQsMulMiyDx4lMAVWROw25qNeOq2S4n13EKDU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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