SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eefe70786ef405015955fd6065a7ece430eeb7fb9414d8fd072766f79ce6be9d' 
  AND token = 'DI6COvRwLBtHoINJKlvfs+pFgrOehBXLmmvWMUolPh4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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