SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cefeff08ed3e47881168f30486ce2a20227f13dee1740ff3bb7cce07083f4890' 
  AND token = 'z2rrjl8ascsF6ZzA8Fxm2ddHp+I3r2bJwtQ90+G+mxk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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