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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1f537501344bf7aa3d2aa2b75086b850d366c6e41c107b0e0cc053f56ee3f11d' 
  AND token = 'G0TRV2E7iDSNw9SMvaPOy+SVGvkkP2JKz+t5ibwFjBE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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