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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2858dc698dd5cf5508be0631c3f61ffe43d00c7c4223fd1e62754e68adf53c1' 
  AND token = 'uPC0it7REj3vTRXPNjtOc1bd0+eOHbQm61PTcE+CJd0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}