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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4668b27df73f34d0428afc9c2427177c8a1d9f4e57a24175c554b1aedac4e634' 
  AND token = 'QjBz32qsSycCCcrPkiSwalO6qXnORUd3+Zef20jRoNM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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