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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5dd90e8c0ef4dfcfff16944c68d6ef4e1e338be76d69c2a85a57cb993a515188' 
  AND token = 'Br8pMkRfpf7GNExhT3Cs28KVrJjKD2ZJ3dd84OXTZu8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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