SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1557531f5da63f950634b78cb89c5d73b0431a2f88516590c699d357528aa334' 
  AND token = 'vfvFqZC3du2dXqyrIGVnelZtegcuYbaOy4MGFdIQ5M8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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