SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73be56d5f7013d02916128f0d275c1df575e88064923313bed10357347f363a9' 
  AND token = 'mmPCPotvz2YUiRZpQ10iSvJxE2cxkizbJCPubIg1fyY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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