SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '925d92408419c8352503b55469ece59c99d51a1dcc3bfd516b041222cdcda538' 
  AND token = 'rrQm4NQLRoWwckBl4t2sK/337nF4lSgSbRGSd0WeYJU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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