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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e0d15e195e7b0eb1a701f053eee6b0a4cf17241a2663c6b0497e2dd556e52c61' 
  AND token = 'c309VDDmF50LvsQ1uxBHPPFi5QnAVkaN8NK+jTTNUQ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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