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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6b8a8e93866ba30a1ea0d1173dc404baecc728d84bb00da63050ea7c19802ca6' 
  AND token = 'U5nCP2YUaOnhhE/P1Whyn2HZv1nlnI9EGSZrTaLSnmg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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