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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9687a0a589829e8dc3f34206d824e2f4d7b8cb314b2bbea50a3643bf47c5a2c7' 
  AND token = 'SJ11lzEMGg7udnHMiowwQGfzMPRsBP8AbCrgkC51tas=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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