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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '56bc2f4f9ac4cf3d6500d2eb0fdecada26f59e9108f2f621ce60492abeef715a' 
  AND token = 'xw+JGnUKZonf4Z0wZb6f0qoqS6ClRKE2mY7RPVbRtGA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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