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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'cbfa0c8e0ec267e4199afd1569eeb2e792578db122fe90a2fc9d5927c8947788' 
  AND token = 'o41JcBPE/xWMSLBnhTp5cRTmzJXGbpbeY5/d5mqMviY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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