SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '626e200180b0f03ec3aff685764ce2647345d014eb8044a193883954b1dfacb2' 
  AND token = 'Nk4NXU8uFQQUIEo6NwMWNrm/sJV98w69DT4ikpRXSn0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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