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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd69f23b2b8233c9fee7ceb1a06b350a13116b1c98f52ed13e9cfaeadb6a95f77' 
  AND token = 'kWAfiFVpltbU83LFK2aeuQHif9/vWdCCt5VqNtawKzM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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