SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd3ad2e642794132582d0984e06622d16d838e9260b990a29db680d3aab42ad7e' 
  AND token = 'vdwxXSlArV1/b2QZ7WYjWpq1EU/isNTzK/dtpFeQN5E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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