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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ba8a9ac947fa3b52bba965d0db9ec3f59b2fcdcdfd5da33b38a6a68f0f44ad59' 
  AND token = 'vsSHLKIcrMEtTLREhg6VpawH6VuxgqhOsyy+lE3mUhE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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