SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9794ef6b896278938537e17acb116347a9219276b087c4e552123120acbf3b9' 
  AND token = 'as1lvkJoSnZqDJhocMMtYVL2HnWFJ/oimbWplEKy0U0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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