SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27c910ab4d445e333a50099f6a029aaaf8294f29eadd919ee6eeed9cb8daaf16' 
  AND token = 'cz5cgKGyvZ5kmmpV0RfZp3DVuH0Tf/60/tCK6RwAm2M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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