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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e4a38ae110ad2aa731024963cdf59e9aaf962ee10d08a97f142ddc4cb4e77621' 
  AND token = 'L4g5TF1cD3EqC3Xp1cYUJRqQenc1QyU8ezojG/Uz0iY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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