SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b3b0eaa79889f4ee0560d966cb0f5fdc74691b80db24728d851e53dd26459a1f' 
  AND token = 'sXql7WOOeCmF0Wel4TCVy/gbTXGbHAJ+gmeTCAIMoeY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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