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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '75d7b1e6f0a7782a3d05e0bea52f28e9e3781e4f54d00c63d2a0a958f08a5030' 
  AND token = 'QHcceaxxqr/oQHt0NUdxk1mf9c4krDI+I4qt22XYWJQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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