SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b720c2da61ce73eb4ff65a52f13b7a05a12ddc673cbdc1d757c1317663f2b593' 
  AND token = '2f69MI8Tx4orHKjvWMYDknelmXXlr3aHcH+8rxhcoJA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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