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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28ab6af1625c7c7f835e31acefa2b6e0ee940d43bd471ecef9d3ff7f2ec0ddc6' 
  AND token = 'zN7yFZcHoMcgRXVkVvwF3kFCVVYr6pFKlbSty4+bbJE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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