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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a42f8e196a3bfd27040324c3c3635d7d329114d82d251bb31cb68b12eff07e43' 
  AND token = '/fHzDER48E2fJ75UoyPGV1xSRTGPXh/MIuOpPzCDC1c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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